Percent Yield in Chemistry
A Grade 9 science worksheet focusing on understanding and calculating percent yield in chemical reactions.
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Percent Yield in Chemistry
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Read each question carefully and answer to the best of your ability. Show all your work for calculation problems.
1. Which of the following best describes the theoretical yield in a chemical reaction?
The amount of product actually obtained from a reaction.
The maximum amount of product that can be formed from given amounts of reactants.
The amount of reactant consumed during the reaction.
The amount of excess reactant remaining after the reaction.
2. Why is the actual yield almost always less than the theoretical yield?
Reactants are always impure.
Some product is always lost during purification or transfer.
Side reactions can occur.
All of the above.
3. The formula for calculating percent yield is (Actual Yield / ) x 100%.
4. A chemical reaction that produces less than 100% yield is considered to be .
5. In a laboratory experiment, some product may be left behind on the glassware, leading to a lower yield.
6. Define 'percent yield' in your own words.
7. A student performs a reaction and calculates a theoretical yield of 15.0 grams. If they actually obtain 12.5 grams of product, what is the percent yield?
8. It is possible for the percent yield of a reaction to be greater than 100%.
True
False
9. A high percent yield always indicates a perfect reaction with no errors.
True
False
10. In the synthesis of aspirin, 10.0 grams of salicylic acid (C7H6O3) reacts with excess acetic anhydride (C4H6O3) to produce aspirin (C9H8O4) and acetic acid (C2H4O2).
The balanced chemical equation is:
C7H6O3 + C4H6O3 → C9H8O4 + C2H4O2
If 11.5 grams of aspirin were actually produced, calculate the percent yield of the reaction. (Molar masses: C7H6O3 = 138.12 g/mol, C9H8O4 = 180.16 g/mol)
